Method for the coloration of concrete and other mixtures

ABSTRACT

The invention concerns a method for the colouring of concrete, and especially in the colours blue or green. According to the method, copper powder from grinding work, for example, may be added before the concrete hardens. This colours the concrete mix due to its reaction with a substance added to the concrete.

Concrete and other mixes using a cement binder have been traditionallycoloured using conventional grey or white cement, which creates anordinary grey tone. Hues other than grey have been created by usingdifferently coloured aggregates or various kinds of powdered pigments.

Concrete can be coloured by adding 0-6 per cent pigment The most usualpigments are metal oxides and earth colours. For example, the use ofmetal oxide is known from EP application 191 278. French patentpublication 2 439 627 describes a method for colouring concrete. TheFrench publication concentrates on colouring an already hardened pieceof concrete, on the assumption that it will be porous enough for thecolour to adhere. Certain kinds of superficial colouration are alwaysweak—as in the above case—because, if a colour solution can enter thepores, so can rainwater, for example, which naturally reduces thepermanence and, quite clearly, the brightness of the colour.

A mortar mixture, intended only for interior use, is also known, inpublication JP 87-37169, which otherwise differs considerably fromcement-based concrete in composition and use. A rust colour is createdin the mortar by adding iron powder and another metal with a lowerionization tendency. The iron oxidizes, forming rust, thus colouring themortar.

Pigments have traditionally been used to colour various kinds ofhardening mixtures based on plastic and resin.

Besides the aforementioned detriments, the methods according to theabove state-of-the-art lack certain hues. In particular, the coloursblue and green are problematic, due to the cost of the pigment needed tocreate them, making the manufacture of the product uneconomical.

The purpose of this invention is to create a method based on acompletely new principle, which will create new kinds of colours forconcrete and similar. These colours are especially, but not solely, blueand green hues. In brief, according to the invention, when metal powderor other fine metal material is mixed into the concrete or other mix,the metal will react chemically to make a compound producing the desiredcolour.

The above and other advantages and benefits of the invention have beencreated using a method with the characteristic features given in theaccompanying claims.

As stated above, the invention is based on adding a metal powder orother relatively fine metal material, such as copper powder or granules,to the mix to be hardened, and treating it with a suitable chemicalsubstance to create the colour. Thus, the chemical substance producingthe colour may be included as a component of the mix itself, or may beadded separately. In particular, but not exclusively—as describedlater—the metal powder or similar may be added to an unhardened concreteor corresponding mix, whence it spreads evenly and thoroughly in themix, becoming bound more permanently than in known methods.

The addition of copper powder to a concrete or corresponding mix coloursthe mix blue or green. As the colouration is extremely strong, adding arelatively small amount of copper is sufficient to create a brightcolour. It is clear that, instead of using copper powder, it is alsopossible to use many other alloys with a copper content, such as brass,bronze or other substances containing copper. Other cheap materials areores that contain copper, and other similar substances that createcolour. Examples of substances that colour the above mixes includeammonium chloride, ammonium carbonate, acetic acid or oxalic acid. Acolour can also be created without adding reagents, due to thesubstances that are naturally in concrete.

Although there are innumerable alternatives for forming colour, thecreation of blue or green colour, as stated above, is particularlyimportant. Familiarity with the known chemical reactions that createcolours from metal powders or similar allows a desired chemicalsubstance to be used to create a reaction. The book, The Colouring,Bronzing and Patination of Metals, by Richard Hughes and Michael Rowe,published by Thames and Hudson Ltd., London, deals extensively withchemical substances used to treat metals.

The essence of the invention is that the colour arises from a chemicalreaction and not, for example, from the mere addition of colouredparticles to the mix. Thus, the permanence of the colour is of a totallydifferent order to that of a colour created only superficially, through,for instance, a surface treatment. An example from a different field isthe permanence of the colour created by a chemical reaction when acopper plate is treated with nitric acid, in comparison with the easilyremovable colour that results from treating the same plate with a coppersulphate solution.

The invention is described in the following text with the aid of threeexamples of manufacture.

EXAMPLE 1

Several doses of 1-5% copper powder or granules are added to theconcrete during manufacture. In one test, grinding waste from metalworkwas used and in another short lengths of waste copper wire. Due to theirgreater specific gravity, the copper powder or granules can, if desired,be made to sink by vibrating the mix. As a result, they settle againstthe facade surface of the piece being cast, and that surface acquires abrighter colour. The colour results when the copper reacts with ammoniumchloride (0.1-0.5%) added to the concrete. The colour can also becreated afterwards in the concrete by treating it with an ammoniumchloride and/or ammonia solution.

EXAMPLE 2

The surface of the formwork fabric is brush or roller-painted with athin (3-10 mm) cement mixture, to which 1-5% copper powder has beenadded. When this is still wet, normal concrete is poured on top of itand adheres to the copper-cement mixture. Thus, it is possible toeconomically manufacture concrete units with a coloured surface, or witha surface that can be coloured according to the basic principlesdescribed above.

EXAMPLE 3

2% copper powder is added to a hardenable mixture of resin and rockmaterial used in sculpture. Ammonium chloride is used to create thecolour. The result is a beautifully coloured material, which is assuitable as the uncoloured material for its purpose.

It is also possible to treat concrete or other mixes with a coppercontent in other ways —for example, in the same way that copper, ormaterials with a copper content, are given a patina. It is also entirelypossible to use suitable chemicals to vary the colour that arisesafterwards, as described in the book referred to above.

The embodiments of the method of the invention can be adapted innumerous ways. For instance, compressed air or another medium can beused to blast a material containing fine copper into the surface of anunhardened concrete or other mix, so that it penetrates for a certaindistance. Clearly, in this case the powder is not spread evenly throughthe entire material, but this is unnecessary, as the coloured surfacelayer is thick enough to withstand wear.

Another adapted embodiment concerns a way of bringing the chemicalsubstance, which creates the colour, into contact with a materialcontaining copper, permitting a colour reaction. Thus, a fabric may beused in the framework The chemical substance can be added in a suitablemanner to the formwork fabric, even if dry. When the moisture of theconcrete being cast in the formwork penetrates the substance, itactivates the property creating a chemical reaction. If desired, thepowder containing copper can be added on top of the formwork fabricbefore casting. In this connection, a net-like material can also be usedas the substance containing copper. Thus the copper colour results froma reaction between the substance contained in the above formwork fabricand the moisture of the concrete.

What is claimed is:
 1. A method for colouring concrete and cement mixesby using a metal component to create the colour, comprising the step of:distributing metal throughout an unhardened concrete or cement mix toreact there chemically to create a colour.
 2. A method according toclaim 1, wherein the metal is copper, or a metal alloy containingcopper, and is added as powder, as granules, as pieces or as a net tothe concrete or cement mix, to create a blue or green hue.
 3. A methodaccording to claim 1, further comprising the steps of: adding a chemicalsubstance which reacts with the metal to create a colour throughout theconcrete or cement mix; and reacting the chemical substance with themetal to create the colour.
 4. A method according to claim 1, furthercomprising the step of: adding waste material containing copper, or orewith a copper content throughout the concrete or cement mix.
 5. A methodaccording to claim 1, further comprising the step of: treating a surfaceof a finished concrete product with a chemical substance to vary the hueobtained.
 6. A method according to claim 3, further comprising the stepof: adding the chemical substance, to a form work fabric comprising theconcrete or cement mix.
 7. A method according to claim 1, wherein thedistributing step comprises: spraying the metal in the form of fineparticles throughout the unhardened concrete or cement mix.
 8. A methodaccording to claim 3, wherein the chemical substance is selected fromthe group of ammonium chloride, ammonium carbonate, oxalic acid andacetic acid.
 9. A method according to claim 2, further comprising theaddition of an ammonia containing composition which reacts with thecopper.
 10. A method according to claim 9, wherein the ammoniacontaining composition is ammonium chloride or ammonium carbonate.
 11. Amethod for colouring concrete and cement mixes by adding copper andammonium chloride or ammonium carbonate throughout an unhardenedconcrete or cement mix.
 12. A method according to claim 11, wherein thecopper or copper alloy is added as a powder, as granules, as pieces, oras a net to the unhardened concrete or cement mix.
 13. The method ofclaim 11, wherein said copper is a copper alloy.
 14. A method forcolouring concrete and cement mixes by using a metal component to createthe colour, comprising the steps of: distributing metal as a powder, asgranules, as pieces, or as a net throughout the unhardened concrete orcement mix; and chemically reacting the metal to create a colour.
 15. Amethod according to claim 14, wherein the metal component is copper or ametal alloy containing copper.
 16. A method according to claim 15,further comprising the step of: adding an ammonia containing compositionwhich chemically reacts with the copper or metal alloy containingcopper.
 17. A method according to claim 16, wherein the ammoniacontaining composition is ammonium chloride or ammonium carbonate.